Abstract

Low-density parity-check (LDPC) coded optical orthogonal frequency division
multiplexing (OFDM) is shown to significantly outperform LDPC coded on-off
keying (OOK) over the atmospheric turbulence channel in terms of both coding
gain and spectral efficiency. In the regime of strong turbulence at a bit-error
rate of 10-5, the coding gain improvement of the LDPC coded
single-side band unclipped-OFDM system with 64 sub-carriers is larger than the
coding gain of the LDPC coded OOK system by 20.2dB for quadrature-phase-shift
keying (QPSK) and by 23.4dB for binary-phase-shift keying (BPSK).